Some responses of Australian researchers to drought and climate

variability?

John Williams,

Commissioner

NSW Natural Resources Commission.

14-15th November 2008Hedley Bull Centre

Australian National University

Drought - Past and Future

An Australian National University Water Initiative

6 November 2002

Riverina

6 November 2002

Riverina….10 minutes later

A well used slide by Peter Cullen

The CSIRO/BOM analysis

shows that

•extent and frequency of exceptionally hot years

have been increasing over

recent decades, and that

trend is expected to continue.

• only some parts of the

country will be affected

• climate change is not

always the culprit.

http://www.bom.gov.au/cgi-bin/silo/reg/cli_chg/timeseries.cgi?variable=raindecile10&region=mdb&season=0112

Rainfall trend (1910 to 2005)

Source: Barry Hanstrum, Bureau of Meteorology

Tasmania Annual Rainfall-anomaly

Tasmania Annual Rainfall-high rainfall years

Tasmania Annual Rainfall-low rainfall years

2 December 2008 20TYPE IN PRESENTATION NAME

Annual Flows In Lachlan River at Forbes

Annual Flows in Lachlan River at Forbes

Annual Flows in Murrumbidgee at Wagga Wagga

Normal Distribution of Rainfall at Burrunjuck

0

0.0005

0.001

0.0015

0.002

0.0025

0 500 1000 1500 2000

Annual Rainfall

1909-1949

1950-1998

Climate Shifts- Implications for Water Availability

Average Rainfall Average Rainfall

has increasedhas increased

but climate but climate

variability has variability has

also increasedalso increased

Source: Shahbaz Khan, CSIRO Land and Water

Changes in Seasonal Flows in MurrumbidgeeChanges in Seasonal Flows in Murrumbidgee

at Balranaldat Balranald

Natural

Conditions

PRE 1949

POST 1949

Natural

Conditions1994

Extraction

Source: Shahbaz Khan CSIRO Land and Water

0

5 ,0 0 0

1 0 ,0 0 0

1 5 ,0 0 0

2 0 ,0 0 0

2 5 ,0 0 0

3 0 ,0 0 0

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0P e r c e n t a g e o f Y e a r s T h a t F l o w is L e s s T h a n V a l u e

Flo

w (

GL

/year)

1 9 9 4 D e v e l o p m e n t

N a t u r a l C o n d i t i o n s

MURRAY RIVER FLOW AT MOUTH

Source: Shahbaz Khan CSIRO Land and Water/Charles Sturt University

Drought and water management– land use

• Change distribution of land-uses to minimise

impacts

• Hazard assessment of economic and

environmental vulnerability to drought

develop maps and analysis

build in climate change

• Use medium-term weather forecasts to predict how drought risk can be minimised

The cycle of R&DBiophysical

knowledge

Risk assessment

& evaluation

•APSIM-Farming

System

models

New production systems

Environmental remediation

Decision support

Drought and water management

- rain fed areas•Risk assessment of current dryland farming

• driven by historical climate and climate

change data

Yield (tonnes/ha)

Probability

Clay soil

Loam soil

Analysis of Drought at Walgett

Soil water store is 190mm

Soil water store is 100mm

Soil water store is 190mm

Location: Walgett

Crop: wheat

Sowing window: 1 May – 31 JulSoil Type: Vertosols, PAWC=240mm

Planting Rules: when 60cm depth 75% full

N Level: N=75kg/ha

NonReset = Continuous simulation from 1889-2000 without resetting the soil profile

Reset = Reset soil nitrogen/organic carbon every year to the same level

Sow date=15-Apr

Sow date=15-May

Sow date=15-Jun

Sow date=15-Jul

Yield (kg/ha)

55005000450040003500300025002000

Pro

bab

ility

90

80

70

60

50

40

30

20

10

Location: Walgett Crop: wheat

Sowing Dates: Fixed sowing on: 15-Apr, 15-May, 15-Jun, 15-Jul

Soil Type: Vertosols, PAWC=240mm

Planting Rules: Assuming profile 2/3 full with water at sowing date

N Level: N=75kg/ha

Weather Data: 1889-2000

Drought and water management

Change in land-use distribution.

• Building on more detailed analysis and measurement on the above to develop for Australia a robust set of maps and analysis that sets out the change in farming and landuse that can greatly reduce the risk of drought damage.

Drought and water management

The development of new farming and forestry systems that do not harm the environment and have capacity to buffer against drought while generating income to support communities must be an urgent goal for rural Australia.

CSIRO LAND and WATER

Improved cropping systems can lead to increased productivity in good years

and can reduce environmental damage in poor years

Mallee 2002

CSIRO LAND and WATERCSIRO LAND and WATER

Waikerie SA: Annual Rainfall 252mm

2002- 110mm (Decile 1)

2002 : -Intensive Cropping with Zero Tillage

-some crop (cash flow)

-stable soil (this years crop and last years stubble)

-ready to crop next year

CSIRO LAND and WATERCSIRO LAND and WATER

Loxton SA: Annual Rainfall 273mm

2002- 106mm (Decile 1)

2002: -Excessive Cultivation

-no stubble protection

-crop lost this year

-soil and nutrients lost

-major restoration required before further production

Drought and water management – new industries

Develop new farming and forestry systems that

• do not harm the environment

• buffer against drought

• generate income from ecosystems service payments to support

communities

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CSIRO Drought and Farming

Drought and farming overviewCSIRO is improving water efficiency and

developing techniques to help farms remain productive during drought conditions.

Drought is a constant threat for Australian farmers. Increasing pressure on water resources means farmers have to be constantly aware of how much water their crops use and how to get the most out of what water is available.

• precision agriculture and spatial modelling tools• developing drought tolerant plants• developing new cropping practices.

• We can reduce the impact of drought in our towns and cities by water re-use, savings and re-plumbing our cities as infrastructure is being replaced in new towns and suburbs.

• 25% of water extracted from our rivers and groundwater is used for urban domestic and industrial use.

• Cities are exporters of water. Overall we only re-use about 11% of our water in urban centers

Drought and water management

Drought and water management

• The science of how rivers and irrigation areas are linked and work as one is critical to Australia getting a water policy environment that can deal better with drought.

• How best to manage our rivers and groundwater systems against the tension between extraction for irrigation and urban use, and the need for environmental flows that can maintain health of rivers, groundwater, wetlands and estuaries

Irrigated Agriculture

CSIRO LAND and WATER

Tension between water extraction and water for river health

Water property rights• Research active in clarifing water property

rights and the obligations associated with those rights to give farmers some certainty and to enable water to be recovered for the environment.

Water LevelSerpentine

DamFeb 2002

(20% reduction in rainfall for

past

26 years)

Climate variability

Climate variability: inflow decrease

0

100

200

300

400

500

600

700

800

900

1000

YE

AR

19

13

19

17

19

21

19

25

19

29

19

33

19

37

19

41

19

45

19

49

19

53

19

57

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61

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65

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69

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73

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81

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19

97

20

01

To

tal a

nn

ua

l in

flo

w (

GL

)

Inflow 1911 to 1974 (338 GL av) 1975 to 2001 (167 GL av)

Note: A year is taken as May to April and labelled year is start (winter) of year

Year 2001 inflows are not for a full year

12%

reduction in Rainfall

results in

25% reduction in

Water Yield

Climate change

Summer Winter

Autumn Spring

Projected Rainfall

Decreases

Projected Rainfall Decreases

CSIRO usually has two voices

• Status quo focus-productivity-survive

• Longer term change implication –environment/social